Targeted Therapy in Oncology: Pharmacological Advances and Clinical Challenges

Abstract

Targeted therapy has fundamentally transformed contemporary oncology by shifting cancer management from empiric cytotoxic chemotherapy toward mechanism-based precision medicine guided by molecular tumor profiling. Unlike conventional chemotherapy, which non-selectively damages rapidly proliferating cells, targeted therapies interact with specific molecular abnormalities that drive malignant transformation and progression. These agents inhibit critical oncogenic pathways involved in cell proliferation, apoptosis evasion, angiogenesis, metastasis, and DNA repair. Major pharmacological classes include monoclonal antibodies directed against extracellular receptors or ligands, small-molecule tyrosine kinase inhibitors (TKIs) targeting intracellular signaling cascades, antibody–drug conjugates (ADCs) enabling selective cytotoxic delivery, and synthetic lethality-based agents such as poly(ADP-ribose) polymerase (PARP) inhibitors designed for tumors with defective homologous recombination repair mechanisms.

Clinical application of targeted therapies has significantly improved response rates, progression-free survival, and overall survival across a wide range of malignancies including breast cancer, non-small cell lung cancer, colorectal cancer, melanoma, and hematological cancers. In several settings, these therapies have converted previously fatal cancers into chronic manageable diseases. However, long-term therapeutic efficacy remains limited by multiple factors, including intrinsic and acquired resistance, clonal tumor heterogeneity, activation of compensatory signaling pathways, biomarker limitations, treatment-related toxicities, and substantial financial burden.

Recent pharmacological advances aim to overcome these challenges through development of next-generation inhibitors active against resistance mutations, rational combination regimens targeting parallel pathways, nanotechnology-based drug delivery systems to enhance tumor selectivity, and real-time molecular monitoring using liquid biopsy. Furthermore, artificial intelligence

assisted predictive modeling is emerging as a promising tool for individualized therapy selection and early detection of therapeutic resistance.

This review provides a comprehensive overview of the pharmacological foundations of targeted anticancer therapy, classification of major drug classes, molecular mechanisms of resistance, and key clinical challenges. It also discusses evolving therapeutic strategies and future directions toward adaptive, data-driven, and fully personalized oncology.